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T: Fachverband Teilchenphysik

T 23: Theoretische Astroteilchenphysik und Kosmologie I

T 23.5: Vortrag

Mittwoch, 17. März 2010, 15:00–15:15, HG XV

Boltzmann equations including quantum coherence — Christian Fidler¹, •Matti Herranen¹, Kimmo Kainulainen^2,3, and Pyry M. Rahkila^2,3 — ¹Institut für Theoretische Physik E, RWTH Aachen University, D - 52056 Aachen, Germany — ²Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyvaskyla, Finland — ³Helsinki Institute of Physics, P.O. Box 64, FIN-00014 University of Helsinki, Finland

Based on the Schwinger-Keldysh formalism, we develop a novel approximation scheme (cQPA) to study the nonequilibrium dynamics of fermionic quantum fields in the limit of weak interactions and slowly varying background. Compared to standard kinetic approach with Boltzmann equations, we are able to include the effects of quantum coherence in the presence of decohering collisions. The key element in our formalism is the finding of new singular shell solutions for 2-point Wightman functions in noninteracting theory, which are located in the phase space at k₀ = 0 in single flavor case and at k₀ = (± ω_i ± ω_j)/2 in the mass basis of multiple flavor mixing fields. These new shell solutions are shown to encode the information on quantum coherence between particles and antiparticles of possibly different flavor states. Imposing this phase space structure as an ansatz to the interacting theory leads to a closed set of equations of motion (extended Boltzmann equations) for the corresponding on-shell distribution functions, with a well defined collision integral. This formalism has potentially a variety of applications in particle physics of the early universe, including baryogenesis, leptogenesis and neutrino flavor oscillations.